This invention relates to lubricating oil compositions. More particularly, this invention relates to lubricating oil compositions containing saligenin derivative salts and salicylates.
The allowable level of sulfur in diesel and gasoline fuels is expected to drop to 15 parts per million (ppm) with zero-sulfur fuel already being introduced in select locations. As a result, a substantial portion of the sulfur in emissions from engines operated with these fuels will be attributed to the lubricant. This will necessitate reduced levels of sulfur in such lubricants. A source of sulfur often found in many of these lubricants comes from sulfonate and phenate detergents. The problem therefore is to provide for a partial or complete replacement for such sulfonate and phenate detergents without reducing the performance attributes of the lubricant.
The present invention provides a solution to this problem by providing lubricating oil compositions containing saligenin derivative salts and salicylates as complete or partial replacements for the sulfonate and phenate detergents. The use of such saliginin derivative salts and salicylates provides the advantage of a sulfur-free detergent that does not reduce the performance attributes of the lubricants, and in at least one embodiment, provides the lubricant with improved high temperature deposit performance, oxidative stability, lead and copper corrosion inhibition, and improved seal compatibility.
This invention relates to a lubricating oil composition, comprising:
(A) a base oil;
(B) an alkali or alkaline earth metal salt of a saligenin derivative represented by the formula; 
wherein in formula (B-I): each X independently is xe2x80x94CHO or xe2x80x94CH2OH; each Y independently is xe2x80x94CH2xe2x80x94 or xe2x80x94CH2OCH2xe2x80x94; wherein the xe2x80x94CHO groups comprise at least about 10 mole percent of the X and Y groups; each M is independently the valance of an alkali or alkaline earth metal ion; each R is independently a hydrocarbyl group containing 1 to about 60 carbon atoms; m is 0 to about 10; n is 0 or 1 provided that when n is 0 the M is replaced with H; and each p is independently 0, 1, 2, or 3; provided that at least one aromatic ring contains an R substituent and that the total number of carbon atoms in all R groups is at least 7; and further provided that one of the X groups can be H;
(C) an alkali or alkaline earth metal salt of a hydrocarbon-substituted salicylic acid; and
(D) a metal salt of a phosphorus-containing compound represented by the formula 
wherein in formula (D-I), X1, X2, X3 and X4 are independently O or S; a and b are independently zero or 1; and R1 and R2 are independently hydrocarbyl groups.
The term xe2x80x9chydrocarbylxe2x80x9d denotes a group having a carbon atom directly attached to the remainder of the molecule and having a hydrocarbon or predominantly hydrocarbon character within the context of this invention. Such groups include the following:
(1) Purely hydrocarbon groups; that is, aliphatic, (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl or cycloalkenyl), aromatic, aliphatic- and alicyclic-substituted aromatic, aromatic-substituted aliphatic and alicyclic groups, and the like, as well as cyclic groups wherein the ring is completed through another portion of the molecule (that is, any two indicated substituents may together form an alicyclic group). Such groups are known to those skilled in the art. Examples include methyl, ethyl, octyl, decyl, octadecyl, cyclohexyl, phenyl, etc.
(2) Substituted hydrocarbon groups; that is, groups containing non-hydrocarbon substituents which do not alter the predominantly hydrocarbon character of the group. Those skilled in the art will be aware of suitable substituents. Examples include hydroxy, nitro, cyano, alkoxy, acyl, etc.
(3) Hetero groups; that is, groups which, while predominantly hydrocarbon in character, contain atoms other than carbon in a chain or ring otherwise composed of carbon atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, nitrogen, oxygen and sulfur.
In general, no more than about three substituents or hetero atoms, and preferably no more than one, will be present for each 10 carbon atoms in the hydrocarbyl group.
Terms such as xe2x80x9calkyl-based,xe2x80x9d xe2x80x9caryl-based,xe2x80x9d and the like have meanings analogous to the above with respect to alkyl groups, aryl groups and the like.
The terms xe2x80x9chydrocarbonxe2x80x9d and xe2x80x9chydrocarbon-basedxe2x80x9d have the same meaning and can be used interchangeably with the term hydrocarbyl when referring to molecular groups having a carbon atom attached directly to the remainder of a molecule.
The term xe2x80x9clowerxe2x80x9d as used herein in conjunction with terms such as hydrocarbyl, alkyl, alkenyl, alkoxy, and the like, is intended to describe such groups which contain a total of up to 7 carbon atoms.
The term xe2x80x9coil-solublexe2x80x9d refers to a material that is soluble in mineral oil to the extent of at least about one gram per liter at 25xc2x0 C.
The term xe2x80x9cTBNxe2x80x9d refers to total base number. This is the amount of acid (perchloric or hydrochloric) needed to neutralize all or part of a material""s basicity, expressed as milligrams of KOH per gram of sample.
The Lubricating Oil Composition
The inventive lubricating oil composition is comprised of one or more base oils which are generally present in a major amount (i.e. an amount greater than about 50% by weight). Generally, the base oil is present in an amount greater than about 60%, or greater than about 70%, or greater than about 75% by weight of the lubricating oil composition.
The inventive lubricating oil composition may have a viscosity of up to about 16.3 cSt at 100xc2x0 C., and in one embodiment about 5 to about 16.3 cSt at 100xc2x0 C., and in one embodiment about 6 to about 13 cSt at 100xc2x0 C.
The inventive lubricating oil composition may have an SAE Viscosity Grade of 0W, 0W-20, 0W-30, 0W-40, 0W-50, 0W-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50, 5W-60, 10W, 10W-20, 10W-30, 10W-40, 10W-50, 10W-60, 15W-30, 15W40 or 15W-50.
The inventive lubricating oil composition may have a sulfur content of up to about 0.25% by weight, and in one embodiment about 0.01 to about 0.25% by weight, and in one embodiment about 0.02 to about 0.25% by weight, and in one embodiment about 0.03 to about 0.25% by weight, and in one embodiment about 0.04 to about 0.25% by weight, and in one embodiment about 0.05 to about 0.25%, and in one embodiment about 0.07 to about 0.25% by weight, and in one embodiment about 0.10 to about 0.25% by weight, and in one embodiment about 0.01 to about 0.20% by weight, and in one embodiment about 0.02 to about 0.20% by weight, and in one embodiment about 0.03 to about 0.20% by weight, and in one embodiment about 0.04 to about 0.20% by weight, and in one embodiment about 0.05 to about 0.20% by weight, and in one embodiment about 0.07 to about 0.20% by weight, and in one embodiment about 0.10 to about 0.20% by weight, and in one embodiment about 0.15 to about 0.20% by weight, and in one embodiment about 0.17% by weight, and in one embodiment about 0.01 to about 0.15% by weight, and in one embodiment about 0.02 to about 0.15% by weight, and in one embodiment about 0.03 to about 0.15% by weight, and in one embodiment about 0.04 to about 0.15% by weight, and in one embodiment about 0.05 to about 0.15% by weight, and in one embodiment about 0.07 to about 0.15% by weight, and in one embodiment about 0.10 to about 0.15% by weight.
The inventive lubricating oil composition may have a boron content of up to about 0.2% by weight, and in one embodiment about 0.01 to about 0.2% by weight, and in one embodiment about 0.015 to about 0.12% by weight, and in one embodiment about 0.05 to about 0.1% by weight.
The inventive lubricating oil composition may have a phosphorus content of up to about 0.1% by weight, and in one embodiment up to about 0.09% by weight, and in one embodiment up to about 0.08% by weight, and in one embodiment up to about 0.075% by weight, and in one embodiment up to about 0.07% by weight, and in one embodiment up to about 0.06% by weight, and in one embodiment up to about 0.05% by weight, and in one embodiment up to about 0.04% by weight, and in one embodiment up to about 0.035% by weight, and in one embodiment up to about 0.03% by weight, and in one embodiment up to about 0.025% by weight, and in one embodiment up to about 0.02% by weight, and in one embodiment up to about 0.015% by weight, and in one embodiment up to about 0.01% by weight. In one embodiment, the phosphorus content is in the range of about 0.01 to about 0.1% by weight, and in one embodiment about 0.01 to about 0.08% by weight, and in one embodiment about 0.02 to about 0.07% by weight, and in one embodiment about 0.02 to about 0.06% by weight, and in one embodiment about 0.03 to about 0.06% by weight.
The ash content of the inventive lubricating oil composition as determined by the procedures in ASTM D-874-96 may be in the range up to about 1.2% by weight, and in one embodiment up to about 1.1% by weight, and in one embodiment from about 0.3 to about 1.2% by weight, and in one embodiment about 0.3 to about 1.1% by weight, and in one embodiment about 0.3 to about 1.0% by weight, and in one embodiment about 0.5 to about 1.0% by weight.
In one embodiment, the inventive lubricating oil composition is characterized by a chlorine content of up to about 100 ppm, and in one embodiment up to about 80 ppm, and in one embodiment up to about 50 ppm, and in one embodiment up to about 30 ppm, and in one embodiment up to about 10 ppm.
In one embodiment, the inventive lubricating oil composition is characterized by a maximum amount of about 0.025% by weight sulfur contributed to the lubricating oil composition by sulfonate detergents, and in one embodiment a maximum amount of 0.02% by weight, and in one embodiment a maximum amount of 0.01% by weight contributed by sulfonate detergents. In one embodiment, the inventive lubricating oil composition is characterized by the absence of sulfonate detergents.
The inventive lubricating oil compositions are useful as lubricating oil compositions for engines such as gasoline powered engines and diesel engines, especially heavy duty diesel engines. The inventive lubricating oil composition, at least in one embodiment, is characterized by a reduced sulfur level when compared to the prior art. In one embodiment, the inventive lubricating oil composition exhibits enhanced high temperature deposit performance, oxidative inhibition, improved seal compatability, and lead and copper corrosion resistance characteristics.
(A) The Base Oil
The base oil used in the inventive lubricating oil composition may be selected from any of the base oils in Groups I-V as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. The five base oil groups are as follows:
Groups I, II and III are mineral oil base stocks.
The base oil may be a natural oil, synthetic oil or mixture thereof. The natural oils that are useful include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as mineral lubricating oils such as liquid petroleum oils and solvent treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinicxe2x80x94naphthenic types. Oils derived from coal or shale are also useful. Synthetic lubricating oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene isobutylene copolymers, etc.); poly(1-hexenes), poly-(1-octenes), poly(1-decenes), etc. and mixtures thereof; alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls, etc.); alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof and the like.
Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils that can be used. These are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having an average molecular weight of about 1000, diphenyl ether of polyethylene glycol having a molecular weight of about 500-1000, diethyl ether of polypropylene glycol having a molecular weight of about 1000-1500, etc.) or mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C3-8 fatty acid esters, or the C13Oxo acid diester of tetraethylene glycol.
Another suitable class of synthetic lubricating oils that can be used comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc.) Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid and the like.
Esters useful as synthetic oils also include those made from C5 to C12 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol, etc.
The synthetic base oil may be a poly-alpha-olefin (PAO). Typically, the poly-alpha-olefins are derived from monomers having from about 4 to about 30, or from about 4 to about 20, or from about 6 to about 16 carbon atoms. Examples of useful PAOs include those derived from octene, decene, mixtures thereof, and the like. These PAOs may have a viscosity from about 2 to about 15, or from about 3 to about 12, or from about 4 to about 8 cSt at 100xc2x0 C. Examples of useful PAOs include 4 cSt at 100xc2x0 C. poly-alpha-olefins, 6 cSt at 100xc2x0 C. poly-alpha-olefins, and mixtures thereof. Mixtures of mineral oil with the foregoing poly-alpha-olefins may be used.
The synthetic base oil may be an oil derived from Fischer-Tropsch synthesized hydrocarbons. Fischer-Tropsch synthesized hydrocarbons are made from synthesis gas containing H2 and CO using a Fischer-Tropsch catalyst. These hydrocarbons typically require further processing in order to be useful as the base oil. For example, the hydrocarbons may be hydroisomerized using the process disclosed in U.S. Pat. Nos. 6,103,099 or 6,180,575; hydrocracked and hydroisomerized using the process disclosed in U.S. Pat. Nos. 4,943,672 or 6,096,940; dewaxed using the process disclosed in U.S. Pat. No. 5,882,505; or hydroisomerized and dewaxed using the process disclosed in U.S. Pat. Nos. 6,013,171, 6,080,301 or 6,165,949. These patents are incorporated herein by reference for their disclosures of processes for treating Fischer-Tropsch synthesized hydrocarbons and the resulting products made from such processes.
Unrefined, refined and rerefined oils, either natural or synthetic (as well as mixtures of two or more of any of these) of the type disclosed hereinabove can be used in the lubricants of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from primary distillation or ester oil obtained directly from an esteri-fication process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those skilled in the art such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products.
(B) Alkali or Alkaline Earth Metal Salt of a Saligenin Derivative
The alkali or alkaline earth metal salt of a saligenin derivative may be a compound represented by the formula 
wherein in formula (B-I): each X independently is xe2x80x94CHO or xe2x80x94CH2OH; each Y independently is xe2x80x94CH2xe2x80x94 or xe2x80x94CH2OCH2xe2x80x94; wherein the xe2x80x94CHO groups comprise at least about 10 mole percent of the X and Y groups; each M is independently a valence of an alkali or alkaline earth metal ion; each R is independently a hydrocarbyl group containing 1 to about 60 carbon atoms; m is 0 to about 10; n is 0 or 1 provided that when n is 0 the M is replaced with H; and each p is independently 0, 1, 2, or 3; provided that at least one aromatic ring contains an R substituent and that the total number of carbon atoms in all R groups is at least 7; and further provided that one of the X groups can be H. In one embodiment, m is 1 to about 10 and one of the X groups is H.
The alkali and alkaline earth metals that are useful include sodium, potassium, lithium, calcium, magnesium, strontium and barium, with calcium and magnesium being especially useful. In formula (B-I), when the metal M is a divalent metal (e.g., calcium or magnesium) the other valence of M, not shown, may be satisfied by other anions or by association with an additional xe2x80x94Oxe2x88x92 functionality of the same saligenin derivative.
In formula (B-I), each n is independently 0 or 1, provided that when n is 0, the M is replaced by H, that is, to form an unneutralized phenolic xe2x80x94OH group. The average value of n is typically about 0.1 to about 1.0. That is, the structure represents a partially or completely neutralized metal salt, a value of 1.0 corresponding to complete neutralization of each site by the metal ion M. The compound contains one aromatic ring or a multiplicity of aromatic rings linked by xe2x80x9cYxe2x80x9d groups, and also xe2x80x9cXxe2x80x9d groups. Since xe2x80x9cmxe2x80x9d can be 0 to about 10, this means that the number of such rings will typically be 1 to about 11, although it is to be understood that the upper limit of xe2x80x9cmxe2x80x9d is not a critical variable. In one embodiment, m is about 2 to about 9, and in one embodiment about 3 to about 8, and in one embodiment about 4 to about 6. One of the X groups can be H.
Most of the aromatic rings in formula (B-I) contain at least one R substituent, which is a hydrocarbyl group, and in one embodiment an alkyl group, containing 1 to about 60 carbon atoms, and in one embodiment about 7 to about 28 carbon atoms, and in one embodiment about 9 to about 18 carbon atoms. R may comprise a mixture of various chain lengths, so that the foregoing numbers represent an average number of carbon atoms in the R groups (number average). R can be linear or branched. Each aromatic ring in the structure may be substituted with 0, 1, 2, or 3 such R groups (that is, p is 0, 1, 2, or 3), most typically 1. Different rings in a given molecule may contain different numbers of such substituents. At least one aromatic ring in the molecule must contain at least one R group, and the total number of carbon atoms in all the R groups in the molecule should be at least about 7, and in one embodiment at least about 12.
In formula (B-I), the X and Y groups may be seen as groups derived from formaldehyde or a formaldehyde source, by condensative reaction with the aromatic molecule. While various species of X and Y may be present, the commonest species comprising X are xe2x80x94CHO (aldehyde functionality) and xe2x80x94CH2OH (hydroxymethyl functionality); similarly the commonest species comprising Y are xe2x80x94CH2xe2x80x94 (methylene bridge) and xe2x80x94CH2OCH2xe2x80x94 (ether bridge). The relative molar amounts of these species in a sample of the above material may be determined by 1H/13C NMR as each carbon and hydrogen nucleus has a distinctive environment and produces a distinctive signal. (The signal for the ether linkage, xe2x80x94CH2OCH2xe2x80x94 must be corrected for the presence of two carbon atoms, in order to arrive at a correct calculation of the molar amount of this material. Such a correction is well within the abilities of the person skilled in the art.)
In one embodiment, X is at least in part xe2x80x94CHO and such xe2x80x94CHO groups comprise at least about 10, and in one embodiment at least about 12, and in one embodiment at least about 15 mole percent of the X and Y groups. In one embodiment, the xe2x80x94CHO groups comprise about 20 to about 60 mole percent of the X and Y groups, and in one embodiment about 25 to about 40 mole percent of the X and Y groups.
In one embodiment, X is at least in part xe2x80x94CH2OH and such xe2x80x94CH2OH groups comprise about 10 to about 50 mole percent of the X and Y groups, and in one embodiment about 15 to about 30 mole percent of the X and Y groups.
In one embodiment in which m is non-zero, Y is at least in part xe2x80x94CH2xe2x80x94 and such xe2x80x94CH2xe2x80x94 groups comprise about 25 to about 55 mole percent of the X and Y groups, and in one embodiment about 32 to about 45 mole percent of the X and Y groups.
In one embodiment, Y is at least in part xe2x80x94CH2OCH2xe2x80x94 and such xe2x80x94CH2OCH2xe2x80x94 groups comprise about 5 to about 20 mole percent of the X and Y groups, and in one embodiment about 10 to about 16 mole percent of the X and Y groups.
The relative amounts of the various X and Y groups depends to a certain extent on the conditions of synthesis of the molecules. Under many conditions the amount of xe2x80x94CH2OCH2xe2x80x94 groups is relatively small compared to the other groups and is reasonably constant at about 13 to about 17 mole percent. Ignoring the amount of such ether groups and focusing on the relative amounts of the xe2x80x94CHO, xe2x80x94CH2OH, and xe2x80x94CH2xe2x80x94 groups, useful compositions have the following relative amounts of these three groups, the total of such amounts in each case being normalized to equal 100%:
The compound represented by formula (B-I) may be a magnesium salt, and the presence of magnesium during the preparation of the compound is believed to be important in achieving the desired ratios of X and Y components described above. (After preparation of the compound, the Mg metal can be replaced by hydrogen, other metals, or ammonium if desired, by known methods.) The number of Mg ions in the composition is characterized by an average value of xe2x80x9cnxe2x80x9d of about 0.1 to about 1.0, and in one embodiment about 0.2 or about 0.4 to about 0.9, and in one embodiment about 0.6 to about 0.8, which correspond to about 20% to about 100%, and in one embodiment about 20% or about 40% to about 90%, and in one embodiment about 60% to about 80% neutralization by Mg. Since Mg is normally a divalent ion, it can neutralize up to two phenolic hydroxy groups. Those two hydroxy groups may be on the same or on different molecules. If the value of n is less than 1.0, this indicates that the hydroxy groups are less than completely neutralized by Mg ions. Alternatively, each Mg ion may be associated with one phenolic anion and an ion of another type such as a hydroxy (OHxe2x88x92) ion or carbonate ion (CO3xe2x88x92), while still providing an n value of 1.0. The specification that the average value of n is about 0.1 to about 1.0 is not directly applicable to basic or overbased versions of this material (described below) in which an excess of Mg or another cation can be present. It should be understood that, even in a basic material, some fraction of the phenolic OH groups may not have reacted with the magnesium and may retain the OH structure.
It is to be understood that in a sample of a large number of molecules, some individual molecules will exist which deviate from these parameters: for instance, there may be some molecules containing no R groups whatsoever. Likewise, some fraction of molecules may contain only one (or even zero) X groups, while some may contain more than two X groups. And some fraction of the aromatic groups may be linked by Y groups to more than two neighboring aromatic groups. These molecules could be considered as impurities, and their presence will not negate the present invention so long as the majority of the molecules of the composition are as described. In any event, compositions exhibiting this type of variability are to be construed as encompassed by the present invention and the description that a material is represented by the formula shown. There is a reasonable possibility that a significant fraction of the polynuclear molecules of the present invention may bear only a single X group. In order to explicitly account for this possibility, it is to be understood that if m is 1 or greater, one (but typically not both) of the X groups in the above structures can be xe2x80x94H.
The salts represented by formula (B-I) can be prepared by combining a phenol substituted by the above-described R group with formaldehyde or a source of formaldehyde and magnesium oxide or magnesium hydroxide under reactive conditions, in the presence of a catalytic amount of a strong base.
Substituted phenols, and alkyl-substituted phenols in particular, are well known items of commerce. Alkylated phenols are described in greater detail in U.S. Pat. No. 2,777,874.
Formaldehyde and its equivalents are likewise well known. Common reactive equivalents of formaldehyde includes paraformaldehyde, trixoane, formalin and methal.
The relative molar amounts of the substituted phenol and the formaldehyde can be important in providing products with the desired structure and properties. In one embodiment, the substituted phenol and formaldehyde are reacted in equivalent ratios of about 1:1 to about 1:3 or about 1:4, and in one embodiment about 1:1.1 to about 1:2.9, and in one embodiment about 1:1.4 to about 1:2.6, and in one embodiment about 1:1.7 to about 1:2.3. Thus, in one embodiment, there is about a 2:1 equivalent ratio of formaldehyde to substituted phenol. (One equivalent of formaldehyde is considered to correspond to one H2CO unit; one equivalent of phenol is considered to be one mole of phenol.) In one embodiment of the Mg species, the mole ratio of alkylphenol:formaldehyde:Mg is about 1:1.4:0.4, that is, for example, about (1):(1.3 to 1.5):(0.3 to 0.5), the amounts being the quantities actually retained in the final product, rather than the amounts charged to the reaction.
The strong base may be sodium hydroxide or potassium hydroxide, and can be supplied in an aqueous solution.
The process can be conducted by combining the above components with an appropriate amount of magnesium oxide or magnesium hydroxide with heating and stirring. A diluent such as mineral oil or other diluent oil can be included to provide for suitable mobility of the components. An additional solvent such as an alcohol can be included if desired, although it is believed that the reaction may proceed more efficiently in the absence of additional solvent. The reaction can be conducted at room temperature or a slightly elevated temperature such as about 35 to about 120xc2x0 C., and in one embodiment about 70 to about 110xc2x0 C., and in one embodiment about 90 to about 100xc2x0 C. The temperature may be increased in stages. When water is present in the reaction mixture it is convenient to maintain the mixture at or below the normal boiling point of water. After reaction for a suitable time (e.g., about 30 minutes to about 5 hours, or about 1 to about 3 hours) the mixture can be heated to a higher temperature, preferably under reduced pressure, to strip off volatile materials. Favorable results may be obtained when the final temperature of this stripping step is about 100 to about 150xc2x0 C., and in one embodiment about 120 to about 145xc2x0 C.
Reaction under the conditions described above leads to a product which has a relatively high content of xe2x80x94CHO substituent groups, that is, about 10%, about 12%, about 15%, or greater.
The hydrocarbon-substituted saligenin salt (B) may be overbased. These overbased salts are sometimes referred to as basic, hyperbased or superbased salts. When these salts are overbased, the stoichiometrically excess metal can be magnesium or it can be another metal or a mixture of cations. The basically reacting metal compounds used to make these overbased salts are usually an alkali or alkaline earth metal compound (i.e., the Group IA, IIA, and IIB metals excluding francium and radium and typically excluding rubidium, cesium and beryllium), although other basically reacting metal compounds can be used. Compounds of Ca, Ba, Mg, Na and Li, such as their hydroxides and alkoxides of lower alkanols are usually used as basic metal compounds in preparing these overbased salts but others can be used as shown by the prior art referred to herein. Overbased salts containing a mixture of ions of two or more of these metals or other cations, including mixtures of alkaline earth metals such as Mg and Ca, can be used.
Overbased materials are generally prepared by reacting an acidic material (typically an inorganic acid, e.g., carbon dioxide, or lower carboxylic acid) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (mineral oil, naphtha, toluene, xylene, etc.) for said acidic organic material, a stoichiometric excess of a metal base, and a promoter. The acidic organic compound will, in the present instance, be the above-described saligenin derivative.
The acidic material used in preparing the overbased material can be a liquid such as formic acid, acetic acid, nitric acid, or sulfuric acid. Acetic acid is particularly useful. Gaseous acidic materials can also be used, such as HCl, SO2, SO3, CO2, or H2S, preferably CO2 or mixtures thereof, e.g., mixtures of CO2 and acetic acid. The acidic material, which may be an acidic gas, is reacted with the mixture under conditions to react, normally, with the majority of, or about 80-90% or about 85-90% of, the stoichiometric excess of the metal base. Strongly acidic materials, however, would normally be used in an amount less than an equivalent of the phenol, while weakly acidic materials such as CO2 can be used in excess.
A promoter is a chemical employed to facilitate the incorporation of metal into the basic metal compositions. The promoters are diverse and are well known in the art. A discussion of suitable promoters is found in U.S. Pat. Nos. 2,777,874, 2,695,910, and 2,616,904. These include the alcoholic and phenolic promoters. The alcoholic promoters include the alkanols of 1 to about 12 carbon atoms such as methanol, ethanol, amyl alcohol, octanol, isopropanol, and mixtures of these. Phenolic promoters include a variety of hydroxy-substituted benzenes and naphthalenes. A particularly useful class of phenols are the alkylated phenols of the type listed in U.S. Pat. No. 2,777,874, e.g., heptylphenols, octylphenols, and nonylphenols. Mixtures of various promoters are sometimes used.
Patents describing techniques for making basic salts of acidic organic compounds generally include U.S. Pat. Nos. 2,501,731; 2,616,905; 2,616,911; 2,616,925; 2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162; 3,318,809; 3,488,284; and 3,629,109.
The saligenin derivative salt (B) may be employed in the inventive lubricating oil composition as a detergent and may therefore be added in a minor detergent amount. The concentration may range of up to about 5% by weight based on the weight of the lubricating oil composition, and in one embodiment about 0.5% to about 5% percent by weight, and in one embodiment about 1% to about 2.5% by weight.
These compounds can be added directly to the lubricating oil composition. In one embodiment, however, they are diluted with a substantially inert, normally liquid organic diluent such as mineral oil, synthetic oil (e.g., ester of dicarboxylic acid), naptha, alkylated (e.g., C10-C13 alkyl) benzene, toluene or xylene to form an additive concentrate. The additive concentrate may then be added to the lubricating oil composition. These concentrates usually contain from about 1% to about 99% by weight, and in one embodiment about 10% to about 90% by weight of the diluent.